Then, New England gave it all away in a fitting end to an ugly 17-10 game.

That is ugly except for Jackson. Tasked with shadowing the NFL's fourth-leading receiver, he more than held his own Sunday. By game's end, the undrafted rookie held the new high bar for defending Smith-Schuster.

Recognizing that Jackson was following their dynamic No. 1B wideout, the Steelers picked on him early.

"Yeah, they came at me, even on the first play they tried to go deep," Jackson remembered of the incompletion.

And late.

Jackson's final pass break-up kept Pittsburgh -- ahead 14-10 with under three minutes left -- from what would have been a game-sealing touchdown. From New England's 30-yard line, Roethlisberger had lofted a long ball to Smith-Schuster, who had been isolated in man coverage against Jackson on third down. Help wasn't coming for the rookie with the game on the line.

Leaping, Smith-Schuster secured an initial catch only to have it broken as they wrestled to the ground. Their last battle left no doubt as to who had won the war.

Pittsburgh kicked a field goal, maintained a one-score lead and Smith-Schuster's night was effectively over at four catches on 10 targets for 40 yards. He'd averaged 94.5 receiving yards per game entering kickoff.

"I felt happy about it. I prepared all week. I just like the competition," Jackson said of the matchup. "He's a great receiver and I just had to compete."

Jackson's teammates recognized his performance for the success it was on its own, and its place within a growing pattern of strong outings for him.

"He did great. Every week, his role has expanded. He's been able to play lights out," safety Duron Harmon said. "Smith-Schuster's been putting on a show all year, and for him to go out there and play the way he did, it speaks volumes on the type of player he is and the type of player he's going to become."

While Stephon Gilmore was plenty busy matching up with Antonio Brown, he could still appreciate the down-to-down work Jackson handled on the opposite side. The rookie's game plan for stopping Smith-Schuster had been Gilmore-esque.

"Get his hands on him," Gilmore said. "JuJu is a deep-ball guy, and JC got good ball skills, can play the ball in the air and is a good matchup for him."

If Jackson keeps playing this way, it won't only be his plan that resembles the Patriots' No. 1 cornerback. It'll be his game, too.

"Playing corner, you find out who you really are when somebody catches balls on you and they keep coming back and (you) keep fighting and making plays," Gilmore said. "And he did that."